Adds craft/src/utils/escape.ts as the single exported escaping/URL-safety
util (escapeHtml, escapeAttr, safeUrl) for later hardening tasks to
consolidate the 27 divergent local copies into. html-export.ts now
imports escapeHtml from it instead of keeping a private copy.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
